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Home > List of blog posts > 1. 实例演示数组与对象的解构 ；2 实例演示常用的流程控制方法
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1. 实例演示数组与对象的解构 ；2 实例演示常用的流程控制方法
a.
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1. 对象解构

  1. <!DOCTYPE html>
  2. <html lang="en">
  3.   <head>
  4.     <meta charset="UTF-8" />
  5.     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  6.     <title>对象和数组解构</title>
  7.   </head>
  8.   <body>
  9.     <script>
  10.       //解析要求等于2边类型相同
  11.       ({ name, age } = { name: "誓言", age: 22 });
  12.       console.log(name, age);
  14.       //支持默认值
  15.       ({ UserName, Age, Sex = "男" } = { UserName: "誓言1", Age: 28 });
  16.       console.log(UserName, Age, Sex);
  18.       //支持别名
  19.       ({ UserName: 姓名, Age, Sex = "男" } = { UserName: "誓言1", Age: 28 });
  21.       console.log("姓名", Age, Sex);
  22.     </script>
  23.   </body>
  24. </html>

2. 数组解构

  1. <!DOCTYPE html>
  2. <html lang="en">
  3.   <head>
  4.     <meta charset="UTF-8" />
  5.     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  6.     <title>对象和数组解构</title>
  7.   </head>
  8.   <body>
  9.     <script>
  10.       //解析要求等于2边类型相同
  11.       ({ name, age } = { name: "誓言", age: 22 });
  12.       console.log(name, age);
  14.       //支持默认值
  15.       ({ UserName, Age, Sex = "男" } = { UserName: "誓言1", Age: 28 });
  16.       console.log(UserName, Age, Sex);
  18.       //支持别名
  19.       ({ UserName: 姓名, Age, Sex = "男" } = { UserName: "誓言1", Age: 28 });
  21.       console.log("姓名", Age, Sex);
  23.       //数组解构
  24.       const color = ["red", "bule", "green"];
  25.       let [c1, c2, c3] = color;
  26.       console.log(c1, c2, c3);
  28.       //多维数组解构
  29.       let [a, [b, c], d] = [1, [2, 3], 4];
  30.       console.log(a, b, c, d);
  32.       //数组也支持默认值
  34.       let [x, y, z = 100] = [100, 200];
  35.       console.log(x, y, z);
  36.     </script>
  37.   </body>
  38. </html>

3.流程控制

3.1. 单分支

  1. let score = 70 ;
  2. if(score >= 60) console.log("及格了");

3.2. 双分支

  1. if(score >= 60) console.log("及格了")
  2. else console.log("不及格");

3.3. 多分支

  1. if (score >= 60 && score <= 80) console.log('合格');
  2. else if (score >= 81 && score <= 100) console.log('学霸');
  3. else if (score >= 100 && score <= 0) console.log('分数无效');
  4. else console.log("不及格");

3.4. switch简化分支

  1. let response = 'Success';
  2. //单值字符串需要格式统一化，使用.tolowerCase()方法，全转为大写或小写
  3. switch(response.toLowerCase()){
  4.     case 'fail':
  5.         console.log('请求失败');
  6.         break;
  7.     case 'success':
  8.         console.log('请求成功');
  9.         break;
  10.     case 'error':
  11.         console.log('参数错误');
  12.         break;
  13.     default:console.log('未知错误');
  14. }

3.5.三元运算

  • 语法：

（判断）? true : false;

  1. let score = 20;
  2. let str = (score >= 60) ? '及格了' ：'补考吧';
  3. console.log(str);

3.6. 循环

一般用来遍历数组
可以用arr.length来获取数组长度

3.6.1 入口判断型

  1. const arr = [1,2,3,4,5];
  2. let i = 0;
  3. while(i < arr.length){
  4. console.log(arr[i]);
  5. i++;
  6. }

3.6.2 出口判断型do...while

do…while不管条件成立不成立都会执行一次，而while只有条件成立都会执行

  1. do{
  2. console.log(arr[i]);
  3. i++;
  4. }while(i < arr.length);

3.6.3 for循环

语法：

for(初始化循环变量;设置循环条件;更新循环条件){...}

  1. const arr = [1,2,3,4,5];
  2. for(let i = 0;i < arr.length; i ++){
  3. //从第三个开始输出
  4. if(i >= 3) console.log(arr[i]);
  5. //或者
  6. if(i < 3) baeak;
  7. console.log(arr[i]);
  8. //continue调出
  10. if(arr[i] % 2 ===0) continue;
  11. console.log(arr[i]);
  13. }

3.6.4 对象的遍历

for in

  1. const arr = [1,2,3,4,5];
  2. const obj = {
  3.     id:10000,
  4.     userName:'誓言',
  5.     email:'php@php.cn'
  6. }
  8. for(let key in obj){
  9.     console.log(`${key} => ${obj[key]}`);
  11. }

for of

  1. for(let val of arr){
  2.     console.log(val);
  3. }

  1. <!DOCTYPE html>
  2. <html lang="en">
  3.   <head>
  4.     <meta charset="UTF-8" />
  5.     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  6.     <title>Document</title>
  7.   </head>
  8.   <body>
  9.     <script>
  10.       const arr = [1, 2, 3, 4, 5];
  11.       const obj = {
  12.         id: 10000,
  13.         userName: "誓言",
  14.         email: "php@php.cn",
  15.       };
  17.       for (let key in obj) {
  18.         console.log(`${key} => ${obj[key]}`);
  19.       }
  20.       for (let val of arr) {
  21.         console.log(val);
  22.       }
  23.     </script>
  24.   </body>
  25. </html>
Correcting teacher：天蓬老师天蓬老师

Correction status：qualified

Teacher's comments：
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